Photographic products and processes



klnited States This invention relates to photography and more particularly to novel photographic products and processes.

One object of this invention is to provide a novel imagereceiving elements for use in color diffusion transfer processes.

Another object of this invention is to provide novel color dilfusion transfer processes utilizing said imagereceiving elements.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order or" one or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description.

The present invention is particularly related to color diffusion transfer processes. In such processes a sheet of photosensitive material is exposed to create therein a latent image. The latent image is developed and, concurrent with and under the control of this development, an imagewise distribution of color-providing materials is formed. At least a portion of these color-providing materials is transferred by means of an alkaline aqueous processing liquid to a superposed imagereceiving element to form a colored positive image thereon. As examples of such processes, mention may be made of the processes claimed and disclosed in the copending US. application of Howard G. Rogers, Serial No. 415,073, filed March 9, 1954, wherein dye developers (i.e., dyes containing a silver halide developing function and capable of developing a latent silver halide image) are the color-providing materials, the processes claimed and disclosed in U.S. Patent No. 2,647,049 issued July 28, 1953 to Edwin H. Land, wherein color developers are employed to develop the latent image and color couplers are the color-providing materials, and the processes disclosed in US. Patent No. 2,774,668 issued December 18, 1956 to Howard G. Rogers, wherein complete, preformed dyes are used as the color-providing substances.

The image-receiving elements used in such processes generally comprise an opaque or transparent support coated with an image-receiving layer of a dyeable material which is permeable to the alkaline aqueous processing solution. In the past, the use of film-forming materials such as polyvinyl alcohol and nylons such as Nylon Type F8 (trade name of E. I. du Pont de Nemours & Co., Wilmington, Delaware, for N-methoxymethyl polyhexamethylene adipamide) as the image-receiving layer has been proposed.

It has been discovered that by using a mixture of polyvinyl alcohol and poly-N-vinylpyrrolidone or a copolymer of vinyl alcohol and N-vinylpyrrolidone as the imagereceiving layer in such proccesses, superior positive color images are obtained. This superiority is especially marked and demonstrable in color diffusion transfer processes of the type wherein azo and anthraquinone dye developers are used. As examples of dye developers, which when used with the image-receiving elements of this invention atent O produce improved color images, mention may be made of 2 [p (2,5' dihydroxyphenethyl) phenylazo] 4 methoxy-l-naphthol and 1-phenyl-3-N-n-butylcarboxami do 4 [p (2',5 dihydroxyphenethyl) phenylazoJ- 5-pyrazolone, disclosed in the copending US. application of Elkan R. Blout, Milton Green and Howard G. Rogers, Serial No. 612,045, filed September 25, 1956; l-[ot-methyl 6,13 bis (2',5' dihydroxyphenyl) diethylamino1- S-nitroanthraquinone, disclosed in the copending US. application of Elkan R. Blout and Myron S. Simon, Serial No. 680,437, filed August 26, 1957; 1-acetyl-3-[fi-(2',5 dihydroxyphenyl) ethyl] 6 [,8 (2,5' dihydroxyphenyl)-ethylamino]-anthrapyridone, disclosed in the copending US. application of Elkan R. Blout, Sidney Kasman and Myron S. Simon, Serial No. 522,848, filed July 18, 1955; 2-[p-(2,5-dihydroxyphenylacetamido)-phenylazo]-4-methoxy-1-naphthol, prepared in accordance with the disclosure of Elkan R. Blout, Saul G. Cohen, Milton Green, Howard G. Rogers, Myron S. Simon and Robert B. Woodward, US. application Serial No. 471,542, filed November 26, 1954; 2-[p-(2,5'-dihydroxyphenyl)-phenylazo]-4-methoxy-1-naphthol, disclosed in the copending U.S. application of Myron 8. Simon, Serial No. 612,053, filed September 25, 1956; 2-[p-(2',5'-dihydroxyphenylthioethyl) phenylazo] 4 methoxy 1- naphthol, disclosed in the copending US. application of Milton Green and Howard G. Rogers, Serial No. 663,- 905, filed June 6, 1957; 2-[p-(2',5-dihydroxyphenylsulfonyl)-phenylazo]-4-methoXy-l-naphthol, disclosed in the copending US. application of Milton Green, Serial No. 680,434, filed August 26, 1957; 1-phenyl-3-homogentisamido 4 [p (2,5 dihydroxyphenethyl) phenylazol-S-pyrazolone, disclosed in the copending US. application of Milton Green and Howard G. \ogers, Serial No. 612,052, filed September 25, 1956.

The novel image-receiving elements containing an image-receiving layer comprising a mixture of polyvinyl alcohol and poly-N-vinylpyrrolidone may be prepared using a suitable support such as cellulose acetate, cellulose acetate-coated baryta paper, etc., which support has been suitably subcoated for proper adhesion of the imagereceiving layer, e.g., subcoated with a mixture of cellulose nitrate and partially hydrolyzed polyvinyl acetate, and coating with an aqueous solution, preferably a 3 to 10% solution, comprising the polyvinyl alcohol and poly-N-vinylpyrrolidone. The coating and drying operations involved may be carried out by methods commonly employed in the art. The ratio of poly-N-pyrrolidone to polyvinyl alcohol is preferably less than 1 to 1 and more preferably about 1 to 3. The concentration of poly-N-vinylpyrrolidone should not be so large as to make the resulting image-receiving layer subject to attack by water or alkali. If the concentration of poly-N- vinylpyrrolidone is too low, the images obtained may have reduced brilliance although the stability will not be aifected.

Poly-N-vinylpyrrolidones and polyvinyl alcohols suitable for use in preparing the image-receiving elements of this invention are readily available commercially. As an example of a suitable poly-N-vinylpyrrolidone, mention may be made of PVP, Type NP K-30 (trade name of General Aniline and Film Corp., New York, New York). The polyvinyl alcohols are preferably selected from the high viscosity, substantially completely hydrolyzedmaterials available. As examples of such alcohols, mention may be made of PVA 91-65 (trade name of E. I. du Pont de Nemours & Co., Wilmington, Delaware, for acid hydrolyzed, high viscosity polyvinyl alcohol) and Gelvatol 2-75 (trade name of Shawinigan Products Corp., New York, New York).

Since both film-forming materials are water soluble, the coating solutions may be readily prepared by dissolving said materials in water. Heat may be used to facilitate solubilization. In a preferred embodiment, the polyvinyl alcohol is crosslinked in order to prevent excessive swelling of the resulting film in subsequent diffusion transfer process. This crosslinl-zing may be carried out by adding a crosslinking agent such as dimethylolurea or glyoxal to the above solution and reacting it in the presence of hydrochloric acid. Before applying the solution, a small amount of a wetting agent may be added to aid in the subsequent coating operation.

The novel image-receiving elements containing an image-receiving layer comprising a copolymer of vinyl alcohol and N-vinyl-pyrrolidone may be prepared by coating a suitably subcoated film base such as cellulose acetate, cellulose acetate-coated baryta paper, etc., with an aqueous solution, preferably a 3 to solution, comprising the copolymer.

The vinyl alcohol N-vinylpyrrolidone copolymer may be prepared by polymerizing vinyl acetate and N-vinylpyrrolidone in the presence of a suitable catalyst such, for example, as azobisisobutyronitrile and hydrolyzing oif the acetate radicals. The molar ratio of N-vinyl-pyrrolidone to vinyl alcohol in the polymer is preferably less than 1 to l and more preferably about 1 to 3.

As noted above, the novel image-receiving elements within the scope of this invention are particularly useful in color diffusion transfer processes employing dye developers, and their superiority is especially marked when monoazo, disazo and anthraquinone dye developers are used. In the dye developer processes a photosensitive element including a silver halide emulsion layer is exposed to create therein a latent image. The latent image is developed in the presence of a dye developer and an imagewise distribution of unreacted dye developer, from which the positive image may be created, is formed. At least a portion of said unreacted dye developer is trans ferred to a superposed image-receiving element to create thereon a positive image. The processes are preferably carried out by disposing the dye developer in the photosensitive element prior to exposure and causing it to be solubilized therefrom by an aqueous alkaline processing liquid which is applied between the superposed photosensitive element and image-receiving element. As the process proceeds, the exposed silver halide is reduced to metallic silver and the portions of dye developer which are oxidized as a result of the silver development are substantially immobilized in situ of the silver image. At least a portion of the unreacted dye developer is imbibed on the superposed image-receiving element to create thereon the positive dye image.

The following nonlimiting examples illustrate the preparation of a novel image-receiving element within the scope of this invention and demonstrates its effectiveness when used in a color diffusion transfer process of the dye developer type.

Example 1 3 gms. of PVA 91-65 and 1 gm. of PVP NP K-30 are added to 90 cc. of water and the resulting composition is heated and stirred until solubilization is complete. The resulting solution is made up to 100 cc. by the addition of 1% hydrochloric acid and then 0.3 gm. of dimethylolurea is added and heating and stirring are continued until the dimethylolurea is completely dissolved. A small amount of a wetting agent is added and the solution, while warm, is coated on a cellulose acetate-coated baryta paper.

A photosensitive element for use with the above imagereceiving element is prepared by coating a gelatin-coated cellulose acetate film base with a solution containing 3% of 2-[p-(2,5dihydroxyphenethyl)-phenylazo]-4 methoxy-l-naphthol (prepared as disclosed in the aforementioned US. application Serial No. 612,045) in a 4% solution of cellulose acetate hydrogen phthalate in an 80 to mixture, by volume, of acetone and methanol. After 4 this coating has dried, a silver iodobromide emulsion is applied.

In using the image-receiving element in a diifusion transfer process, the above photosensitive element is exposed and the image-receiving element is superposed thereon as an aqueous processing composition comprising:

Percent Sodium carboxymethyl cellulose 4.5 l-phenyl-B-pyrazolidone 0.2 Sodium hydroxide 2.0 Potassium bromide 0.2

is applied. After an imbibition period of approximately one minute, the image-receiving element is separated and contains a magenta positive image of the subject.

Example 2 A photosensitive element similar to that described in Example 1 is prepared. Processing of the exposed photosensitive element in a manner similar to that employed in Example 1 using as the image-receiving element a layer of polyvinyl alcohol (cast from a 4% aqueous polyvinyl alcohol solution) on a cellulose acetate-coated baryta paper support gives a magenta positive image.

Example 3 Use of a photosensitive element prepared and processed similar to that described in Example 1 using as the imagereceiving element a sheet of cellulose acetate-coated baryta coated with a 4% solution of Nylon Type F8 in ethanol gives a magenta image.

A comparison of the positive images obtained in the above examples shows the image on the poly-N-vinylpyrrolidone-polyvinyl alcohol image-receiving element to have superior over-all quality as compared with either nylon or polyvinyl alcohol. Thus, it is more brilliant than the image on polyvinyl alcohol and almost as brilliant as the image on nylon. Upon exposing the image to a sun lamp for seventy-two hours, at 50% relative humidity, the image on the polyvinyl alcohol poly-N-vinylpyrrolidone element was more stable than the image on the nylon element and almost as stable as the image on the polyvinyl alcohol element.

The following nonlimiting example illustrates the preparation of a vinyl alcohol-N-vinylpyrrolidone copolymer for use in preparing the novel image-receiving elements of this invention.

Example 4 20 gms. (0.23 mol) of vinyl acetate and 5 gms. (.045 mol) of N-vinylpyrrolidone are dissolved in 20 ml. of benzene and are polymerized in the presence of 0.1 gm. of azobisisobutyronitrile for eighteen hours at 66 C. in the absence of air. The reaction medium is diluted with benzene and the resulting polymer is precipitated in hexane and dried. Upon hydrolysis in ethanol and sodium methoxide, a copolymer containing about 25 mol percent N-vinylpyrrolidone and about mol percent vinyl alcohol is produced.

When an image-receiving element is made from the above copolymer and said image-receiving element is used in color diifusion transfer processes, such as above, the brilliance and stability of the images are substantially equivalent to that obtained using the mixture of polyvinyl alcohol and poly-N-vinylpyrrolidone polymers.

It is apparent that by selecting a film base from among suitable known opaque and transparent materials, reflection or transparent prints may be obtained.

It should be noted that other materials useful in the diffusion transfer processes may be incorporated into the image-receiving layer. As examples of such materials, mentoin may be made of dye mordants, oxidizing agents, and acids and alkalies for pH adjustments.

It should also be noted that the image-receiving elements herein set forth are also suitable for use in multicolor transfer processes such as those set forth in the previously mentioned U.S. Patent No. 2,647,049.

Since certain changes may be made in the above prodnot and processes without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a process of forming a photographic image in color, wherein a latent image contained in an exposed silver halide emulsion is developed with an aqueous alkaline solution containing a dye developer to provide in said emulsion a predetermined distribution of unoxidized dye developer, said dye developer being a compound which is both a dye and a silver halide developing agent, and wherein at least part of said distribution of said unoxidized dye developer is transferred by imbibition from said emulsion to an image-receiving element in superposed relationship with said emulsion to impart to said imagereceiving element a reversed positive dye image of the developed image; the improvement characterized by the feature that said image-receiving element comprises an image-receiving layer of a dyeable material selected from the class consisting of (a) copolymers of vinyl alcohol and N-vinylpyrrolidone and (b) mixtures of polyvinyl alcohol and poly-N-vinylpyrrolidone.

2. A process as defined in claim 1 wherein said dye developer is an azo dye developer.

3. A process as defined in claim 1 wherein said dye developer is an anthraquinone dye developer.

4. A process as defined in claim 1 wherein said dyeable material is a mixture of polyvinyl alcohol and poly-N- vinylpyrrolidone and the ratio of poly-N-vinylpyrrolidone to polyvinyl alcohol in said mixture is less than 1 to 1 by weight.

6 5. A process as defined in claim 1 wherein said dyeable material is a mixture of polyvinyl alcohol and poly-N- vinylpyrrolidone and the ratio of poly-N-vinylpyrrolidone to polyvinyl alcohol in said mixture is about 1 to 3 by weight.

6. A process as defined in claim 1 wherein said dyeable material is a copolymer of vinyl alcohol and N-vinylpyrrolidone and the ratio of N-vinylpyrrolidone segments to vinyl alcohol segments in said copolymer is less than 1 to 1 on a molar basis.

7. A process as defined in claim 1 wherein said dyeable material is a copolymer of vinyl alcohol and N-vinylpyrrolidone and the ratio of N-vinylpyrrolidone segments to vinyl alcohol segments in said copolymer is about 1 to 3 on a molar basis.

References Cited in the file of this patent UNITED STATES PATENTS 2,719,831 Craemer et a1. Oct. 4, 1955 2,774,668 Rogers Dec. 18, 1956 2,802,735 Land Aug. 13, 1957 2,834,676 Stanley et a]. May 13, 1958 2,853,417 Werner Sept. 23, 1958 FOREIGN PATENTS 687,751 Great Britain Feb. 18, 1953 1,003,577 Germany Feb. 28, 1957 1,004,043 Germany Mar. 7, 1957 OTHER REFERENCES Vinyl and Related Polymers, Schildknecht, 1952, pp. 677-678. 

1. IN A PROCESS OF FORMING A PHOTOGRAPHIC IMAGE IN COLOR, WHEREIN A LATENT IMAGE CONTAINED IN AN EXPOSED SILVER HALIDE EMULSION IS DEVELOPED WITH AN AQUEOUS ALKALINE SOLUTION CONTAINING A DYE DEVELOPER TO PROVIDE IN SAID EMULSION A PREDETERMINED DISTRIBUTION OF UNOXIDIZED DYE DEVELOPER, SAID DYE DEVELOPER BEING A COMPOUND WHICH IS BOTH A DYE AND A SILVER HALIDE DEVELOPING AGENT, AND WHEREIN AT LAST PART OF SAID DISTRIBUTION OF SAID UNOXIDIZED DYE DEVELOPER IS TRANSFERRED BY IMBITITION FROM SAID EMULSION TO AN IMAGE-RECEIVING ELEMENT IN SUPERPOSED RELATIONSHIP WITH SAID EMULSION TO IMPART TO SAID IMAGERECEIVING ELEMENT A REVERSED POSITIVE DYE IMAGE OF THE DEVELOPER IMAGE, THE IMPROVEMENT CHARACTERIZED BY THE FEATURE THAT SAID IMAGE-RECEIVING ELEMENT COMPRISES AN IMAGE-RECEIVING LAYER OF A DYEABLE MATERIAL SELECTED FROM THE CLASS CONSISTING OF (A) COPOLYMERS OF VINYL ALCOHOL AND N-VINYLPYRROLIDONE AND (B) MIXTURES OF POLYVINYL ALCOHOL AND POLY-N-VINYLPYRROLIDONE. 